Filter assembly for a reprocessor

ABSTRACT

The present invention provides a method of operating a reprocessor that has a chamber for receiving items to be sterilized. The reprocessor is filled with water that has passed through a first and a second filter element that both comprise a filtration system. A liquid sterilant is generated by mixing the water with dry chemical reagents. The liquid sterilant is circulated through a fluid circulation system and the filtration system wherein a portion of the liquid sterilant is directed through a bypass conduit and another portion is directed through the first and second filter elements. After a predetermined exposure time, the reprocessor is drained. Then the reprocessor is filled with water for rinsing that has passed through the first and the second filter elements. The water for rinsing is heated prior to being introduced into the reprocessor.

FIELD OF THE INVENTION

The present invention relates to microbial deactivation of medical,dental, pharmaceutical, veterinary or mortuary instruments and devices,and more particularly to a filtration system for use in a liquidmicrobial deactivation system.

BACKGROUND OF THE INVENTION

Medical, dental, pharmaceutical, veterinary or mortuary instruments anddevices that are exposed to blood or other body fluids require thoroughcleaning and microbial deactivation or sterilization between each use.Liquid microbial deactivation systems are now widely used to clean anddeactivate instruments and devices that cannot withstand the hightemperatures of a steam sterilization system. Liquid microbialdeactivation systems typically operate by exposing the medical devicesand/or instruments to a liquid disinfectant or sterilizationcomposition, such as peracetic acid or some other strong oxidant.

In such systems, the instruments or devices to be cleaned are typicallyplaced within a chamber within the liquid microbial deactivation system,or in a container that is placed within the chamber. During adeactivation cycle, a liquid disinfectant is then circulated through aliquid circulation system that includes the chamber (and the containertherein).

Following the deactivation cycle, a rinse solution, typically water, iscirculated through the chamber to remove traces of the microbialdeactivate and any particulate that may have accumulated on theinstruments or devices during the deactivation cycle. As will beappreciated, it is important to have rinse water of high purity toinsure that the microbially deactivated instruments and devices do notbecome re-contaminated during the rinse cycle.

The water used to rinse the instruments and devices generally passesthrough a filtration system to remove mycobacterium particulates fromthe water. Although small amounts of the liquid sterilant may back-up tothe downstream side of the filtration system, the upstream contents ofthe filtration system are generally not microbially deactivated and/orsterile. Thus, there is a possibility that microbial contamination mayaccumulate in the upstream side of the filtration system over time, andsubsequently pass into the downstream side of the filtration system andbe introduced into the chamber during a rinse cycle.

The present invention overcomes these and other problems and provides animproved filtration system for filtering water used in a microbialdeactivation system.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, there isprovided a method of operating a sterilizer having a chamber forreceiving items to be sterilized, a fluid circulation system forcirculating fluids through the chamber, means for generating a liquidsterilant from dry chemical reagents by mixing water therewith, and awater filtration system for filtering water entering the sterilizer. Thefiltration system includes a fluid feed line that is attached to thechamber, a directional valve disposed in the fluid feed line, and afirst filter element in the fluid feed line. The first filter element isfor filtering fluids therethrough and is located downstream of thedirectional valve between the directional valve and the chamber. Asecond filter element is disposed in the fluid feed line for filteringfluids flowing therethrough. The second filter element is locatedbetween the first filter element and the chamber. A water line isconnected to the fluid feed line at an intersection located between thedirectional valve and the first filter element. A bypass line isconnected to the fluid feed line to define a fluid path that bypassesthe directional valve and the first and second filter elements. Themethod of operating comprises the steps of:

a) filling the sterilizer with water from a water source, by passing thewater through the first and second filter elements;

b) generating a liquid sterilant by mixing water filtered by the firstand second filter elements with the dry chemical reagents;

c) circulating the liquid sterilant through the fluid circulation systemand the filtration system wherein a portion of the liquid sterilant isdirected through the first and second filter elements, and a portion isdirected through the bypass conduit;

d) draining the sterilizer after a predetermined exposure time;

e) passing water for rinsing through the first and second filterelements;

f) heating the water for rinsing after the water for rinsing has passedthrough the first and second filter elements; and

g) introducing the water for rinsing into the chamber.

In accordance with another aspect of the present invention, there isprovided a method of operating a reprocessor having a chamber forreceiving items to be microbially deactivated, a fluid circulationsystem for circulating fluids through the chamber, means for generatinga microbial deactivation fluid from dry chemical reagents by mixingwater therewith, and a water filtration system for filtering waterentering the reprocessor. The filtration system includes a fluid feedline that is connectable to a source of pressurized water, a firstfilter element, and a second filter element. The first filter elementand the second filter element are disposed in the fluid feed line suchthat the second filter element is located downstream from the firstfilter element. A bypass line is connected to the fluid feed line todefine a fluid path that bypasses the first and second filter elements.The water filtration system is connected to the fluid circulationsystem. The method of operating comprises the steps of:

a) filling the reprocessor with water from a water source, by passingthe water through the first and second filter elements;

b) generating a microbial deactivation fluid by mixing water filtered bythe first and second filter elements with the dry chemical reagents;

c) circulating the microbial deactivation fluid through the fluidcirculation system and the filtration system, wherein a portion of themicrobial deactivation fluid is directed through the fluid feed line andanother portion is directed through the first and second filterelements;

d) draining the reprocessor after a predetermined exposure time;

e) filling the reprocessor with water for rinsing, by passing the waterfor rinsing through the first and second filter elements; and

f) heating the water for rinsing prior to introduction of the water forrinsing into the chamber.

In accordance with another aspect of the present invention, there isprovided a method of operating a reprocessor. The reprocessor has achamber for receiving items to be microbially deactivated, a fluidcirculation system for circulating fluids through the chamber, means forgenerating a microbial deactivation fluid from dry chemical reagents bymixing water therewith, and a water filtration system for filteringwater entering the reprocessor. The filtration system includes a fluidfeed line that is connectable to a source of pressurized water. A firstfilter element, a second filter element, and a heater are disposed inthe fluid feed line such that the second filter element is downstreamfrom the first filter element and the heater is downstream of the secondfilter element. A bypass line is connected to the fluid feed line todefine a fluid path that bypasses the first and second filter elementsand the heater. The water filtration system is connected to the fluidcirculation system. The method of operating comprises the steps of:

a) filling the sterilizer with water from a water source, by passing thewater through the first and second filter elements;

b) generating a liquid sterilant by mixing the filtered water with thedry chemical reagents;

c) circulating the liquid sterilant through the fluid circulation systemand the filtration system, wherein a portion of the liquid sterilant isdirected through the fluid feed line and another portion is directedthrough the first and second filter elements to produce filtered liquidsterilant; and

d) operating the heater during the circulating step.

In accordance with yet another aspect of the present invention, there isprovided a reprocessor having a circulation system for circulating aliquid sterilant or microbial deactivation fluid through a chamber thatforms a part of the circulation system and a water filtration system forfiltering water used in the reprocessor. The water filtration systemincludes a fluid feed line that forms a portion of the circulationsystem. One end of the fluid feed line is in fluid communication withthe chamber. A directional valve is disposed in the fluid feed line. Afirst filter element is located upstream from the chamber and isdisposed in the fluid feed line for filtering fluids flowingtherethrough. A second filter element is disposed in the fluid feed linefor filtering fluids flowing therethrough. The second filter element islocated between the first filter element and the chamber. A water lineis connectable to a source of pressurized water and is connected to thefluid feed line at a location between the directional valve and thefirst filter element. A bypass line is connected to the fluid feed lineto defme a fluid path that bypasses the first and second filterelements. The bypass line is connected at one end to the fluid feed lineupstream of the directional valve and is connected at another end to thefluid feed line between the second filter element and the chamber.

In accordance with yet another aspect of the present invention, there isprovided a sterilizer having a chamber for receiving items to besterilized, a fluid circulation system for circulating fluids throughthe chamber, means for generating a liquid sterilant from dry chemicalreagents by mixing water therewith, and a water filtration system forfiltering water entering the sterilizer. The filtration system includesa fluid feed line that is attached to the chamber, a directional valvethat is disposed in the fluid feed line, a first filter element disposedin the fluid feed line for filtering fluids therethrough. The firstfilter element is located downstream of the directional valve betweenthe directional valve and the chamber. A second filter element isdisposed in the fluid feed line for filtering fluids flowingtherethrough. The second filter element is located between the firstfilter element and the chamber. A water line is connected to the fluidfeed line at an intersection located between the directional valve andthe first filter element. A bypass line is connected to the fluid feedline to define a fluid path that bypasses the directional valve and thefirst and second filter elements. The method of operating includes thesteps of:

a) filling the sterilizer with water from a water source, by passing thewater through the first and second filter elements;

b) generating a liquid sterilant by mixing water filtered by the firstand second filter elements with the dry chemical reagents; and

c) circulating the liquid sterilant through the fluid circulation systemand the filtration system, wherein a portion of the liquid sterilant isdirected through the first and second filter elements and a portion isdirected through the bypass conduit.

In accordance with yet another aspect of the present invention, there isprovided a reprocessor having a chamber for receiving items to bemicrobially deactivated or sterilized, a fluid circulation system forcirculating fluids through the chamber, means for generating a microbialdeactivation fluid from dry chemical reagents by mixing water therewith,and a water filtration system for filtering water entering thereprocessor. The filtration system includes a fluid feed line that isconnectable to a source of pressurized water, a first filter element,and a second filter element. The first and second filter elements aredisposed in the fluid feed line such that the second filter element isdownstream from the first filter element. There is provided a method ofchecking the integrity of at least one of the filter elements thatincludes the steps of:

a) establishing a first known pressure on the upstream side of thefilter element;

b) allowing pressure on the upstream side of the filter element todissipate through the filter element and through a leak orifice of knowndimensions;

c) monitoring over time the change in pressure on the upstream side ofthe filter;

d) establishing a second known pressure on the upstream side of thefilter element;

e) allowing pressure on the upstream side of the filter element todissipate through the filter element;

f) monitoring over time the change in pressure on the upstream side ofthe filter; and

g) determining a flow rate through the filter based on the changes inpressure determined in steps c) and f).

One advantage of the present invention is the provision of asterilizable water filtration system for a reprocessing system.

Another advantage of the present invention is the provision of amicrobially deactivated filtration system for a microbial deactivationsystem.

Another advantage of the present invention is the provision of afiltration system as described above that reduces the likelihood ofmicrobial contamination of a water supply as a result of microbialgrowth in a filter element.

A still further advantage of the present invention is a filtrationsystem as described above that is capable of providing a high level ofassurance that the water that is supplied downstream of the secondfilter element is microbially deactivated or sterile.

These and other objects will become apparent from the followingdescription of one embodiment taken together with the accompanyingdrawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in certain parts and arrangement ofparts, one embodiment of which will be described in detail in thespecification and illustrated in the accompanying drawings which form apart hereof, and wherein:

FIG. 1 is a schematic view of a microbial deactivation system;

FIG. 2 is a schematic view of a filtration system, illustrating oneembodiment of the present invention;

FIG. 3 is a partial view of the filtration system shown in FIG. 2,showing an alternate embodiment thereof; and

FIG. 4 is a schematic view of a filtration system, illustrating yetanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein the showings are for the purposeof illustrating one embodiment of the invention only, and not for thepurpose of limiting same, FIG. 1 shows a simplified, schematic pipingdiagram of a microbial deactivation apparatus 10 illustrating oneembodiment of the present invention.

A panel 22, that is part of a housing structure (not shown), defines arecess or cavity 24 dimensioned to receive items or instruments to bemicrobially deactivated. In the embodiment shown, a tray or container 26is provided to receive the devices or instruments to be deactivated.Container 26 is dimensioned to be received within recess or cavity 24,as illustrated in FIG. 1.

A manually operable lid 32 is movable between an opened positionallowing access to cavity 24, and a closed position (shown in FIG. 1)closing or covering cavity 24. A seal element 34 surrounds cavity 24 andforms a fluid-tight, i.e., an airtight and liquid-tight, seal betweenlid 32 and panel 22 when lid 32 is in a closed position. Latch means(not shown) are provided for latching and securing lid 32 in a closedposition during a deactivation cycle. Cavity 24 essentially defines achamber 36 when lid 32 is in a closed position.

A fluid circulation system 40 provides the microbial deactivation fluidto chamber 36 and is further operable to circulate the microbialdeactivation fluid through chamber 36. Fluid circulation system 40includes a water inlet line 42 that is connected to a source of heatedwater (not shown). A pair of filter elements 44, 46 are provided inwater inlet line 42 to filter large contaminants that may exist in theincoming water. Filters 44, 46 are size exclusion filter elements, whichremove particles of a certain size. Filter element 46 preferably filtersout smaller particles than filter element 44. Filter element 44preferably filters out particles of about 3 microns (μ) or larger, andfilter element 46 preferably filters out particles of about 0.1 microns(μ) or larger. Pressure sensors (not shown) may be provided to monitorpressure drops across filter elements 44, 46, a change in the pressuredrop across a filter element being indicative of clogging, rupturing orthe like. Basically, filter elements 44, 46 are provided to filter outparticles found in the water source used to supply apparatus 10. A viralreduction device 52 for inactivating organisms within the water sourceis preferably provided in water inlet line 42. Viral reduction device 52is preferably an ultraviolet (UV) treatment device, and more preferablya class A device, as defined by NSF/ANSI Standards 55, or equivalent,although other viral reduction devices are contemplated. In oneembodiment, a UV light system manufactured by Wedeco Ideal Horizons ofCharlotte, N.C., having a minimum dosage of 40,000 μ W/cm², is used. Inthe embodiment shown, viral reduction device 52 is shown downstream fromfilter elements 44, 46. It is contemplated that viral reduction device52 could be disposed in water inlet line 42 upstream of filter elements44, 46.

A water valve 54 controls the flow of water from water inlet line 42 toa system feeder line 62. System feeder line 62 includes a filtrationsystem 100 to filter microscopic organisms and particles from theincoming water so as to provide microbially deactivated or sterile waterto fluid circulation system 40. System feeder line 62 splits into afirst branch feeder line 64 and a second branch feeder line 66. Firstbranch feeder line 64 communicates with container 26 within chamber 36.Second branch feeder line 66 is connected to chamber 36 itself. Asecondary branch feeder line 68 splits off of first branch feeder line64 and is directed to the inlet portion of chemical delivery dispensingcontainer 72 that contains dry chemical reagents that, when combinedwith water, form the antimicrobial fluid used in the deactivationsystem. A valve 74 controls flow through first branch feeder line 64 andthrough secondary branch feeder line 68 to chemical dispensing container72. Chemical dispensing container 72 is disposed within a well 76 formedwithin panel 22 of the housing. Flow restrictors 78 in second branchfeeder line 66 and secondary branch feeder line 68 regulate fluid flowtherethrough.

A branch return line 82 extends from chemical dispensing container 72and is connected to a system return line 88. Likewise, branch fluidreturn lines 84, 86 extend from container 26 and chamber 36 respectivelyand are connected to system return line 88. System return line 88connects back with water inlet line 42 and fluid feeder line 62, asillustrated in FIG. 1. A pump 92 is disposed within system return line88. Pump 92 is operable to circulate fluid through fluid circulationsystem 40. A drain line 94 is connected to system return line 88. Adrain valve 96 controls fluid flow to drain line 94.

Referring now to FIG. 2, water filtration system 100 is best seen. Waterfiltration system 100 is disposed within fluid feeder line 62 andincludes two filter elements 114 and 134, shown as part of filterassemblies 110, 130. Filter elements 114, 134 are disposed in series influid feeder line 62. A first section 62 a of fluid feeder line 62communicates water inlet line 42 to the inlet side of first filterassembly 110. A second section 62b of fluid feeder line 62 connects theoutlet side of first filter assembly 110 to the inlet side of secondfilter assembly 130. A third section 62 c of fluid feeder line 62connects the outlet side of second filter assembly 130 to a heater 102that is schematically illustrated in FIG. 2. Heater 102 is dimensionedto be able to heat water flowing through third section 62 c of fluidfeeder line 62 to a temperature of at least 95° C.

First filter assembly 110 includes housing 112 and an internal filterelement 114. Filter element 114 is a bacterial retentive size exclusionfilter that preferably filters out mycobacterium particles that arenominally 0.12 microns (μ) or greater. Filter element 114 may include acylindrical support layer (not shown), such as a polypropylene, ahomopolymer surrounded by a filter membrane, such as a hydrophilicpolyvinylidene difluoride (PVDF) or a polyethersulfone (PES) membrane.The filter membrane may be in the form of a capillary tube or hollowfiber member (or “fiber”), or in the form of a tubular sheath of a filmformed either on the inner or outer surface of a tubular macroporoussupport, or a laminate sheet or film, or a laminate film deposited onthe porous support. Suitable filter elements are obtainable from PTITechnologies of Oxnard, Calif.

Filter element 114 defines an annular outer chamber 116 and innerchamber 118. Outer chamber 116 represents the upstream, pre-filtrationside of filter element 114, and inner chamber 118 of the filter assemblyrepresents the downstream, filtered side of filter element 114. As shownin the drawings, first section 62 a of fluid feeder line 62 communicateswith outer chamber 116 of first filter assembly 110, and second section62 b of feeder line 62 communicates with inner chamber 118 of firstfilter assembly 110. A drain line 122 communicates with outer chamber116 of first filter assembly 110. Valve 124 is disposed within drainline 122 to regulate flow from first filter assembly 110 to a drain.

Second filter assembly 130 includes housing 132 and an internal filterelement 134. Filter element 134 is a bacterial retentive size exclusionfilter that preferably filters out mycobacterium particles that arenominally 0.12 microns (μ) or greater. Filter element 134 may include acylindrical support layer, such as a polypropylene, a homopolymersurrounded by a filter membrane, such as a hydrophilic polyvinylidenedifluoride (PVDF) or a polyethersulfone (PES) membrane. The filtermembrane may be in the form of a capillary tube or hollow fiber member(or “fiber”), or in the form of a tubular sheath of a film formed eitheron the inner or outer surface of a tubular macroporous support, or alaminate sheet or film, or a laminate film deposited on the poroussupport. Suitable filter elements are obtainable from PTI Technologiesof Oxnard, Calif. Filter element 134 defines an annular outer chamber136 and inner chamber 138. Outer chamber 136 represents the upstream,pre-filtration side of filter element 134, and inner chamber 138 offilter assembly 130 represents the downstream, filtered side of filterelement 134. As shown in the drawings, second section 62 b of feederline 62 communicates with outer chamber 136 of second filter assembly130 and third section 62 c of feeder line 62 communicates with innerchamber 138 of second filter assembly 130. Drain line 142 communicateswith outer chamber 136 of second filter assembly 130. A valve 144 isdisposed within drain line 142 to regulate flow from second filterassembly 130 to a drain.

Both first and second filter assemblies 110, 130 are preferablypre-sterilized or microbially deactivated, prior to installation, sothat the contents of filter assemblies 110, 130 are free of microbialcontaminants. As will be described in greater detail below, filterassemblies 110, 130 are microbially deactivated or sterilized duringeach subsequent processing phase.

A first pair of valves 152, 154 is disposed in fluid feeder line 62 toenable isolation of first filter assembly 110. In this respect, valve152 is disposed within first section 62 a of fluid feeder line 62 at theinlet side of first filter assembly 110, and valve 154 is disposed infeeder line section 62 b at the outlet side of first filter assembly110. Similarly, a second pair of valves 162, 164 is provided in fluidfeeder line 62 to enable isolation of second filter assembly 130. Inthis respect, valve 162 is disposed in fluid line section 62 b at theinlet side of second filter assembly 130, and valve 164 is provided influid feeder line section 62 c at the outlet side of second filterassembly 130.

A filter bypass line 172 communicates with fluid feed line 62 onopposite sides of first and second filter assemblies 110, 130.Specifically, one end of bypass line 172 is connected to fluid feed line62 between pump 92 and the location where water inlet line 42 connectsto fluid feed line 62. A directional check valve 174 is disposed betweenwater inlet line 42 and filter bypass line 172 to prevent incoming waterfrom communicating with filter bypass line 172, as shall be described ingreater detail below. The other end of filter bypass line 172communicates with feeder line 62 beyond filter assemblies 110, 130 andheater 102.

In accordance with another aspect of the present invention, a filterpurge manifold system 180 is provided. Filter purge manifold system 180is comprised of air inlet line 182 that is operable to provide clean,filtered, pressurized air to circulation system 40. A control valve 184is disposed within air inlet line 182 to regulate the flow of airtherethrough. The air in air inlet line 182 is preferably at apredetermined, regulated pressure. In this respect, air inlet line 182may include a pressure regulator (not shown) for maintaining a generallyconstant, desired air pressure within air inlet line 182. Air inlet line182 splits into two branch return lines 192, 194. A vent line 188 withcontrol valve 189 is connected to branch return lines 192, 194, asillustrated in FIG. 2. Vent line 188 is provided to allow release of airfrom water filtration system 100 during a fill cycle, as shall bedescribed in greater detail below.

First branch line 192 extends through housing 112 of first filterassembly 110 and communicates with outer chamber 116 of first filterassembly 110. Control valve 196 in first branch line 192 regulates theflow of air therethrough. Second branch line 194 extends through housing132 of second filter assembly 130 and communicates with outer chamber136 of second filter element assembly 130. A control valve 198 isdisposed within branch line 194 to regulate flow therethrough.

A first pressure sensor 202 is provided across first section 62 a ofsystem feeder line 62 and branch line 192 to sense pressure on theupstream side of filter element 114.

A second pressure differential sensor 204 is provided across secondsection 62 b of system feeder line 62 and branch line 194 to sensepressure on the upstream side of filter element 134.

A first leak orifice line 212 is connected to first section 62 a offluid feed line 62 between the water inlet valve 54 and valve 152 on theupstream side of first filter assembly 110. A valve 214 within leakorifice line 212 regulates flow therethrough. A flow restrictor 215 isdisposed in leak orifice line 212 to regulate flow therethrough.

A second leak orifice line 216 is connected to second section 62 b offluid feed line 62 between valve 154 on the outlet side of first filterassembly 110 and valve 162 on the inlet side of second filter assembly130. Valve 218 within leak orifice 216 regulates flow therethrough. Aflow restrictor 219 is disposed in leak orifice line 216 to regulateflow therethrough. A drain line 232 is connected to section 62 b ofsystem feeder line 62 on the downstream side of filter element 114. Avalve 234 regulates flow therethrough. A drain line 236 is connected tosection 62 c of system feeder line 62 on the downstream side of filterelement 134. A valve 238 regulates flow therethrough.

A system microprocessor (not shown) controls the operation ofcirculation system 40 and the valves therein, as shall be described ingreater detail below. The operation of circulation system 40 includes afill phase, a chemical generation and exposure phase, a drain phase, oneor more rinse phases, and a filter check phase, as shall also bedescribed in greater detail below.

The present invention shall now further be described with reference tothe operation of apparatus 10 and water filtration system 100. One ormore items to be microbially deactivated or sterilized, such as medical,dental, pharmaceutical, veterinary or mortuary instruments or otherdevices are loaded into chamber 36. In the embodiment shown, the itemswould be loaded into container 26, which in turn would be placed intochamber 36. The items may be supported in a tray, basket, cartridge orthe like (not shown) within chamber 36 or container 26.

The items are microbially deactivated or sterilized with a microbialdeactivation fluid, such as a peracetic acid solution, which in oneembodiment is formed by exposing and mixing dry chemical reagents withinthe chemical dispensing device 72 with incoming water. In this respect,at the beginning of a deactivation or sterilization operation, drainvalve 96 in circulation system 40 is closed, and water valve 54 in inletline 42 is opened to allow heated water to enter circulation system 40.Incoming water is first filtered by filter elements 44, 46 in waterinlet line 42 that, as indicated above, remove particles above a certainsize. Filter elements 44, 46 are sized to successively filter outsmaller sized particles. Incoming water is then treated by a viralreduction device 52 that applies ultraviolet (UV) radiation to the waterto inactivate organisms therein. The incoming water passes through thevalve 54 and enters circulation system 40. The incoming water is thenfiltered by filter assemblies 110, 130 in feeder line 62 and proceeds tofill circulation system 40, chamber 36 and container 26.

Check valve 174 between water inlet valve 54 and filter bypass line 172causes all of the incoming water to flow through the first and secondfilter assemblies 110, 130, thereby insuring filtration of the waterflowing into apparatus 10.

The incoming water is under pressure from an external source, and forcesair in fluid circulation system 40, chamber 36 and container 26 to anover-flow/air device (not shown) that is typically disposed at thehighest point of apparatus 10. Air within the system migrates toward theover-flow device.

The presence of the water flowing through the over-flow block isindicative that apparatus 10 is filled with water. The system controllerthen causes water valve 54 to close, thereby stopping the flow of waterinto apparatus 10, i.e., into fluid circulation system 40, chamber 36and container 26. The foregoing description basically describes a waterfill phase of apparatus 10.

Once apparatus 10 is filled, the system controller initiates ageneration and exposure phase of operation, wherein pump 92 is energizedto circulate water through circulation system 40, chamber 36 andcontainer 26. Valve 74 in first branch feeder line 64 is opened tocreate flow through chemical dispensing container 72. The water and drychemical reagents within chemical dispensing container 72 form amicrobial deactivation fluid that, as indicated above, in one embodimentof the invention, is peracetic acid. The deactivation fluid formed fromthe dry chemical reagents flows into circulation system 40, wherein itis circulated through circulation system 40, chamber 36 and container 26by pump 92. In this respect, as indicated in the drawings, a portion ofthe microbial deactivation or sterilant fluid flows into chamber 36around container 26 and a portion of the microbial deactivation fluidflows into and through container 26 and the items contained therein.

As indicated by the arrows in FIG. 2, a portion of the circulateddeactivation fluid flows through filter bypass line 172 and a portion ofthe deactivation fluid flows through feed line 62 through filterassemblies 110, 130. The amount of fluid flowing through the respectiveportions of the system may be controlled by a regulating valve 222disposed within filter bypass line 172 or fluid feed line 62.Preferably, a major portion of the deactivation fluid flows throughfilter bypass line 172. The portion of the deactivation fluid flowingthrough filter feed line 62 and through the first and second filterassemblies 110, 130 is preferably such to insure deactivation of filterelements 114, 134 by exposure to the deactivation fluid. In thisrespect, the flow of the deactivation fluid through filter assemblies110, 130 microbially deactivates or sterilizes filter elements 114, 134and inactivates any microbial contamination that may have entered intofilter assemblies 110, 130 during the water fill phase. Thus, duringeach operation of apparatus 10, filter elements 114, 134 are exposed toa microbial deactivation or sterilant fluid to microbially deactivate orsterilize same. Moreover, the microbial deactivation fluid that flowsthroughout the closed-loop, fluid circulation system 40 during adeactivation phase, effectively decontaminates fluid circulation system40, and the components and fluid conduits forming the same. In otherwords, fluid circulation system 40 is decontaminated during eachdecontamination cycle.

After a predetermined exposure period, a drain phase is initiated. Drainvalve 96 is opened and the microbial deactivation fluid is drained fromthe re-circulation system, chamber 36 and container 26.

After the microbial deactivation fluid has been drained from apparatus10, one or more rinsing phases is performed to rinse any residualmicrobial deactivation fluid and any residual matter from thedeactivated items. In this respect, inlet valve 54 is opened tointroduce fresh water into apparatus 10, in a manner as heretoforedescribed as the fill phase. All incoming water passes water filtrationsystem 100 wherein water entering circulation system 40 and chamber 36is microbially deactivated or sterile. After each rinse fill, the rinsewater is drained from apparatus 10 as heretofore described. Pump 92 maybe activated to circulate the rinse water through apparatus 10. Duringeach fill, circulation and drain phase, the fluid over-flow/air make-upassembly operates to prevent microbial contaminants from entering theinternal environment within the system.

Following the rinse phase(s), first and second filter assemblies 110,130 undergo a filter integrity test to insure that both first and secondfilter assemblies, and more specifically, filter elements 114, 134 areoperating properly. Prior to conducting the filter integrity test, thefilter housings 112, 132 are preferably drained by first closing valves152, 154, 164 thereby isolating valve assemblies 110, 130 fromfiltration system 100 and from each other, and then opening valves 124,144, 234 and 238 in drain lines 122, 142, 232 and 236, respectively.Valves 189, 196 and 198 are opened to allow vent air to filter housings112, 132 to facilitate draining thereof. As will be appreciated,incoming air is filtered by filter means (not shown) to preventcontaminants from entering filter assemblies 110, 130. When filterassemblies are drained, drain valves 124, 144 and vent valve 189 areclosed.

Water filtration system 100 is then tested for any leak(s) and to insurethat leak orifices 212, 216 are not clogged or obstructed. In thisrespect, each filter assembly 110, 130 and associated connections definea “test area.” Basically, the “test area” for first filter assembly 110is defined by filter assembly 110 and the tubing or pipe connectionsbetween valves 54, 124, 154, 196 and 234. Similarly, the “test area” forsecond filter assembly 130 is defined by filter assembly 130 and thetubing or pipe connections between valves 154, 144, 238, 164 and 198. Toconduct the leak test, valves 54, 154 and 164 remain closed to isolatefirst and second filter assemblies 110, 130 from fluid circulationsystem 40 and from each other. Valves 124, 144, 234 and 238 in lines122, 142, 232 and 236, respectively, are closed to close-off any outletsfrom filter housings 112, 132, respectively. Valves 152, 162 are in anopened position. Valves 196, 198 are initially closed. Valve 184 in airinlet line 182 is then opened. As indicated above, the air pressure inair inlet line 182 is maintained at a set pressure level. Valves 196 and198 in branch lines 192, 194, respectively, are then opened to exposethe “test areas” to the set pressure. Once the pressure in therespective test areas stabilizes, valves 196 and 198 are closed therebyisolating the respective test areas from air inlet line 182. Pressuredifferential sensors 202, 204 compare the pressure within the test areasto the set pressure within air inlet line 182. If no leaks exist in thetest pressure area, no difference in pressure should be sensed by firstand second pressure differential sensors 202, 204. No change in pressureis indicative of no leaks within filter housings 112, 132 or the testpressure areas associated therewith. Valves 214 and 218 in leak orificelines 212, 216 are then opened to allow the “set pressure” to leak orvent from the respective test pressure areas. First and second pressuredifferential sensors 202, 204 will sense a change in the differentialpressure between the respective test pressure areas and the set pressurewithin air inlet line 182. This pressure change is indicative that leakorifices 212, 216 are not clogged or obstructed. No change in thedifferential pressure between a test area and the set pressure in airinlet line 182 is indicative that the leak orifice in the test area isclogged.

Following the aforementioned test to determine the integrity of the testarea and the proper operation of the leak orifices, a water filterintegrity test is conducted. According to one embodiment, the filterintegrity test is a two-step process. In this respect, valves 54, 154and 164 are closed to isolate first and second filter assemblies 110,130 from fluid circulation system 40 and from each other. Valves 152,162 are in an opened position. Valves 124, 144, 234, 238 in drain lines122, 142, 232, 236 are closed. Valves 214, 218 in leak orifice lines212, 216 are closed.

Valve 184 in air inlet 182 is then opened to allow pressurized air inbranch lines 192, 194. As indicated above, the air pressure in air inletline 182 is maintained at a set pressure level. Valves 196, 198 infeeder lines 192, 194 are then opened to allow pressurized air into therespective test areas associated with each filter assembly 110, 130.After a predetermined period of time wherein pressure in the respectivetest areas stabilizes at the aforementioned set pressure level, valves196, 198 are closed.

With the pressure within the respective test areas stabilized to the“set pressure,” valves 234, 238 in drain lines 232, 236 respectively,and valves 214, 218 in leak orifice lines 212, 216 are opened. As willbe appreciated, a pressure differential will then exist across filterelements 114, 134 and through flow restrictions 215, 219 in leak orificelines 212, 216. In other words, lower pressure exists in inner chamber118, 138 of filter assemblies 110, 130 because valves 234, 238 connectinner chamber 118, 138 to drain. Likewise, leak orifice lines connect tothe atmosphere, thereby establishing a lower pressure beyond flowrestrictions 215, 219. The higher pressure in outer chambers 116, 136slowly dissipates through filter elements 114, 134 and through flowrestriction 215, 219 of leak orifice lines 212, 216. Differentialpressure sensors 202, 204 sense the difference in pressure between theinner chambers 118, 138, and the set pressure level in line 182. Thesystem controller monitors the change in pressure differential over timeand determines a pressure drop per unit time Q_(sys) for each respectivetest area. Q_(sys) is the pressure drop per unit time caused by thepressure dissipating through filter elements 114, 134 and leak orificelines 212, 216. Measuring the rate of change of pressure through filterelements 114, 134 and through leak orifice lines 212, 216, represent thefirst step in the two-step filter check.

Upon completion of the first step, valves 214, 218 in leak orifice lines212, 216, and valves 234, 238 in drain lines 232, 236 are closed. Valves196, 198 are then opened to re-establish the set pressure level in therespective test areas for filter assemblies 110, 130. Valves 196, 198are then closed. Valves 234, 238 in drain lines 232, 236 are thenopened. Valves 214, 218 in leak orifice lines 212, 216 remain closed.The system controller monitors over time the change in pressuredifferential senses by differential pressure transducers 202, 204 aspressure dissipates through filter elements 114, 134. In this respect,the second step of the filter check process repeats the first step, butwith leak orifices 215, 219 closed. The system controller monitors thechange in pressure differential over time and determines a pressure dropper unit time Q_(filter) for each respective test area. Q_(filter) isthe pressure drop per unit time caused by pressure dissipating through afilter element alone.

With the foregoing data, the system controller determines whether thepressure changes are indicative of proper flow through filter elements114, 134. In this respect, the system controller determines thedifference between Q_(sys) and Q_(filter). This difference represents apressure drop per unit of time Q_(orif) of the leak orifice only. Thesystem controller then determines a unit of pressure per volume value,CAL, by dividing Q_(orif) by Q_(cal). Q_(cal) is a calibrated volumetricflow rate of the leak orifice at the desired test, i.e., set pressure.The CAL value is the relationship between the volumetric flow rate ofthe orifice and the corresponding pressure drop caused to the system inunits of pressure per volume. A calculated, diffusion-of-flow rate,Q_(calc), for a respective water filter element is then determined bydividing Q_(swf) by CAL. The calculated value is the calculated,diffusion-of-flow rate of the filter based upon the filter pressure dropand the orifice. An abnormal pressure change is indicative that a defectexists in a filter elements 114, 134, thereby indicating the need forreplacement of filter assembly 110 or filter assembly 130, and that asterile or microbially deactivated operation may not have been performedby apparatus 10. In this respect, the failure of filter element 114 orfilter element 134 is indicative that water may not have been filteredto a desired level and that contaminated water may have entered chamber36. While the operation of one of the two filter elements 114, 134 isbelieved to provide sufficient filtration to insure microbiallydeactivated or sterile water, it is preferred that apparatus 10 indicatea faulty operation in the event that it senses even one defective filterelement 114 or 134.

Although the foregoing leak test, leak orifice integrity test and filterintegrity test were generally described as occurring simultaneously, itis contemplated that such tests for the respective filter assemblies110, 130 and associated test areas could be performed independently.

The present invention thus provides a water filtration system 100 foruse in a sterilant or microbial deactivation reprocessor that reducesthe likelihood of microbial contamination being introduced into achamber 36 by the incoming water.

Referring now to FIG. 3, a water filtration system 100′ according to analternate embodiment of the present invention is shown. Basically, FIG.3 shows a bypass system 300 to allow second filter assembly 130 to bebypassed during a processing phase. In this respect, it is believed thatthe microbial deactivation fluid can degrade certain filter elementsrendering it less effective for water purification. For example,surfactants present in the microbial deactivation fluid may cause afilter to become blocked, particularly if the filter pore size isextremely small. Accordingly, it may be desirable to limit the exposureof second filter assembly 130 to the deactivation fluid. In theembodiment shown, a bypass line 302 is connected at one end to secondsection 62 b of fluid feeder line 62, and at its other end to thirdsection 62 c of fluid feeder line 62. A valve 304 controls the flowthrough bypass line 302. Valve 304 is a normally closed valve therebyblocking flow through bypass line 302 when fluid flows through secondfilter assembly 130. Second filter assembly 130 may be bypassed byclosing valves 162, 164 and by opening valve 304 in bypass line 302thereby causing fluid flowing through the fluid feeder line to bypasssecond filter assembly 130. The embodiment in FIG. 3 is controlled bythe system controller to operate during a microbial deactivation fluidgeneration and circulation phase thereby preventing the deactivationfluid from flowing through second filter assembly 130. During a waterinlet phase or a rinse phase, the controller would control therespective valves 304, 162, 164 to allow the incoming water to flowthrough second filter assembly 130 thereby providing sterile ormicrobially deactivated water for each fill and rinse phase.

Referring now to FIG. 4, an alternate embodiment of water filtrationsystem 100 having a single filter assembly 410 is shown. Filter assembly410 includes a housing 412 and two (2) internal filter elements 414,416. Both filter elements 414 and 416 are bacteria-retentive, sizeexclusion filters that preferably filter out mycobacterium particlesthat are nominally 0.12 microns (μ) or greater. Filter elements 414, 416may include cylindrical support layers (not shown), such aspolypropylene, a homopolymer surrounded by a filter membrane, such as ahydrophilic polyvinylidene difluoride (PVDF) or a polyethersulfone (PES)membrane. The filter membrane may be in the form of a capillary tube orhollow fiber member (or “fiber”), or in the form of a tubular sheet of afilm formed either on the inner or outer surface of a tubular macroporous support, or a laminate sheet or film, or a laminate filmdeposited on the porous support. An annular outer chamber 422 is definedbetween outer filter element 414 and housing 412. An intermediatechamber 424 is defined between outer filter element 414 and inner filterelement 416. An inner chamber 426 is defined by filter element 416. Asillustrated in FIG. 4, filter assembly 410 is disposed in system feederline 62. Drain line 142 communicates with outer chamber 422, and drainline 236 communicates with inner chamber 426.

As illustrated by the arrows in FIG. 4, fluid flowing through systemfeeder line 62 flows first through outer filter element 414 and thenthrough inner filter element 416. In this respect, inner filter 416 isdown line from outer filter element 414. Accordingly, filter assembly410 provides the same filtering effects as the embodiment shown in FIG.2. However, the single filter assembly 410 reduces the number of valvesand connections of water filtration system 100 thereby increasing thereliability and performance thereof. In addition to simplifying theoverall structure, eliminating a filter cartridge and reducing thenumber of connecting lines, the overall volume of circulation system 40is thereby reduced, thereby reducing the amount of liquid chemistryrequired within the system. It will also be appreciated that theaforementioned leak test, leak orifice integrity test and filterintegrity test may likewise be conducted on filter assembly 410 and anassociated “test area.”

The foregoing description is a specific embodiment of the presentinvention. It should be appreciated that this embodiment is describedfor purposes of illustration only, and that numerous alterations andmodifications may be practiced by those skilled in the art withoutdeparting from the spirit and scope of the invention.

In accordance with another embodiment of the present invention, heater102 in third section 62 c of fluid feeder line 62 is operated to heatwater flowing through section 62 c to a temperature sufficient toinactivate viruses in water that has passed through first and secondfilter assemblies 110, 130. As indicated above, viral reduction device52, that is preferably an ultraviolet (UV) treatment device, treatsincoming water to inactivate organisms therein. Heater 102 is utilizedas a second viral reduction device in conjunction with, or as analternative to, viral reduction device 52. In this respect, heater 102also treats incoming water to inactivate organisms therein. In oneembodiment of the present invention, water flowing through third section62 c of fluid feeder line 62 is heated by heater 102 to a temperaturebetween about 40° C. and about 95° C. In another embodiment of thepresent invention, the water flowing through third section 62 c of fluidfeeder line 62 is heated to a temperature between about 55° C. and about85° C. In a more preferred embodiment, the water is heated to atemperature between about 75° C. and about 85° C.

Preferably, heater 102 is used as a viral reduction device only during arinse phase(s) of the decontamination cycle. In this respect, waterentering circulation system 40 and chamber 36 during a fill phase ismicrobially decontaminated or sterilized as a result of the sterilizingchemicals introduced into the water from chemical delivery dispensingcontainer 72 during the chemical generation and exposure phase of theoperation of circulation system 40. Accordingly, any viral contaminationexisting within water in apparatus 10 is inactivated by such chemicals.Because no deactivating chemicals or sterilants are introduced into therinse water, heater 102 is utilized to inactivate any viruses that maybe present in the water following filtration by first and second filterassemblies 110, 130 before such water enters chamber 36 during a rinsephase(s). In this manner, the sterility of the instruments withinchamber 36 is further ensured.

While heater 102 is preferably used to inactivate viruses during a rinsephase(s) of the decontamination cycle, it would be appreciated thatheater 102 may also be used to heat water entering chamber 36 during thechemical generation and exposure phases. In this respect, thedecontaminating properties of chemicals introduced by chemicaldispensing container 72 may be enhanced by heating such chemicals duringthe chemical generation and exposure phases of the operating cycle.

Heater 102 can also be used to heat fluid circulating through fluidcirculation system 40 during the deactivation phase during which fluidcirculates through fluid circulation system 40.

It is intended that all such modifications and alterations be includedinsofar as they come within the scope of the invention as claimed or theequivalents thereof.

1. A method of operating a sterilizer having a chamber for receivingitems to be sterilized, a fluid circulation system for circulatingfluids through said chamber, means for generating a liquid sterilantfrom dry chemical reagents by mixing water therewith, and a waterfiltration system for filtering water entering said sterilizer, saidfiltration system including: a fluid feed line that is attached to saidchamber, a directional valve disposed in said fluid feed line, a firstfilter element in said fluid feed line, for filtering fluidstherethrough, said first filter element located between said directionalvalve and said chamber and downstream of said directional valve, asecond filter element in said fluid feed line for filtering fluidsflowing therethrough, said second filter element located between saidfirst filter element and said chamber, a water line connected to saidfluid feed line at an intersection located between said directionalvalve and said first filter element, and a bypass line connected to saidfluid feed line to define a fluid path that bypasses said directionalvalve and said first and second filter elements, said method ofoperating comprising the steps of: filling said sterilizer with waterfrom a water source, by passing said water through said first and secondfilter elements; generating a liquid sterilant by mixing water filteredby said first and second filter elements with said dry chemicalreagents; circulating said liquid sterilant through said fluidcirculation system and said filtration system wherein a portion of saidliquid sterilant is directed through said first and second filterelements, and a portion is directed through said bypass conduit;draining said sterilizer after a predetermined exposure time; passingwater for rinsing from said water line through said first and secondfilter elements; heating said water for rinsing after said water forrinsing has passed through said first and second filter elements; andintroducing said water for rinsing into said chamber.
 2. A method ofoperating a sterilizer as defined in claim 1, wherein said second filterelement is capable of filtering smaller particles than said first filterelement.
 3. A method of operating a sterilizer as defined in claim 1,further comprising the step of exposing said water for rinsing to UVradiation before said water for rinsing passes through said first andsecond filter elements.
 4. A method of operating a sterilizer as definedin claim 1, further comprising the step of testing the integrity of saidfilter elements after each sterile processing phase.
 5. A method ofoperating a sterilizer as defined in claim 1, wherein said water forrinsing is heated to a temperature of from about 40° C. to about 95° C.6. A method of operating a sterilizer as defined in claim 1, whereinsaid water for rinsing is heated to a temperature of from about 55° C.to about 85° C.
 7. A method of operating a sterilizer as defined inclaim 1, wherein said water for rinsing is heated to a temperature offrom about 75° C. to about 85° C.
 8. A method of operating a reprocessorhaving a chamber for receiving items to be microbially deactivated, afluid circulation system for circulating fluids through said chamber,means for generating a microbial deactivation fluid from dry chemicalreagents by mixing water therewith, and a water filtration system forfiltering water entering said reprocessor, said filtration systemincluding: a fluid feed line connectable to a source of pressurizedwater, a first filter element and a second filter element in said fluidfeed line, said second filter element disposed in said fluid feed linedownstream from said first filter element, and a bypass line connectedto said fluid feed line to define a fluid path that bypasses said firstand second filter elements, said water filtration system being connectedto said fluid circulation system, said method of operating comprisingthe steps of: filling said reprocessor with water from a water source,by passing said water through said first and second filter elements;generating a microbial deactivation fluid by mixing water filtered bysaid first and second filter elements with said dry chemical reagents;circulating said microbial deactivation fluid through said fluidcirculation system and said filtration system wherein a portion of saidmicrobial deactivation fluid is directed through said fluid feed lineand another portion is directed through said first filter element andsaid second filter element; draining said reprocessor after apredetermined exposure time; filling said reprocessor with water forrinsing, by passing said water for rinsing through said first and secondfilter elements; and heating said water for rinsing prior tointroduction of said water for rinsing into said chamber.
 9. A method ofoperating a reprocessor as defined in claim 8, wherein said secondfilter element is capable of filtering smaller particles than said firstfilter element.
 10. A method of operating a reprocessor as defined inclaim 8, further comprising the step of exposing said water to UVradiation before said water for rinsing passes through said first andsecond filter elements.
 11. A method of operating a reprocessor asdefined in claim 8, further comprising the step of testing the integrityof said filter elements after each microbially deactivated processingphase.
 12. A method of operating a reprocessor as defined in claim 8,wherein said water for rinsing is heated to a temperature of from about40° C. to about 95° C.
 13. A method of operating a reprocessor asdefined in claim 8, wherein said water for rinsing is heated to atemperature of from about 55° C. to about 85° C.
 14. A method ofoperating a reprocessor as defined in claim 8, wherein said water forrinsing is heated to a temperature of from about 75° C. to about 85° C.15. A method of operating a reprocessor having a chamber for receivingitems to be microbially deactivated, a fluid circulation system forcirculating fluids through said chamber, means for generating amicrobial deactivation fluid from dry chemical reagents by mixing watertherewith, and a water filtration system for filtering water enteringsaid reprocessor, said filtration system including: a fluid feed lineconnectable to a source of pressurized water, a first filter element anda second filter element in said fluid feed line, said second filterelement being downstream from said first filter element, a heater beingdownstream of said first and said second filter elements and a bypassline connected to said fluid feed line to define a fluid path thatbypasses said first and second filter elements and said heater, saidwater filtration system being connected to said fluid circulationsystem, said method of operating comprising the steps of: filling saidsterilizer with water from a water source, by passing said water throughsaid first and second filter elements; generating a liquid sterilant bymixing said filtered water with said dry chemical reagents; circulatingsaid liquid sterilant through said fluid circulation system and saidfiltration system wherein a portion of said liquid sterilant is directedthrough said fluid feed line and another portion is directed throughsaid first filter element and said second filter element to producefiltered liquid sterilant; and operating said heater during saidcirculating step.
 16. A method of operating a sterilizer as defined inclaim 15, wherein said second filter element is capable of filteringsmaller particles than said first filter element.
 17. A method ofoperating a reprocessor as defined in claim 15, further comprising thestep of exposing said water to UV radiation before said water passesthrough said first and second filter elements.
 18. A method of operatinga reprocessor as defined in claim 15, further comprising the step oftesting the integrity of said filter elements after each microbiallydeactivated processing phase.
 19. A method of operating a reprocessor asdefined in claim 15, wherein said water for rinsing is heated to atemperature of from about 40° C. to about 95° C.
 20. A method ofoperating a reprocessor as defined in claim 15, wherein said water forrinsing is heated to a temperature of from about 55° C. to about 85° C.21. A method of operating a reprocessor as defined in claim 15, whereinsaid water for rinsing is heated to a temperature of from about 75° C.to about 85° C.
 22. A method of operating a reprocessor as defined inclaim 15, wherein said heater is operated to heat said filtered waterduring said step of filling said sterilizer.
 23. A method of operating areprocessor as defined in claim 22, further comprising the step ofexposing said water to UV radiation before said water passes throughsaid first and second filter elements.
 24. In a reprocessor having acirculation system for circulating a liquid sterilant or microbialdeactivation fluid through a chamber that forms a part of saidcirculation system, a water filtration system for filtering water usedin said reprocessor, said water filtration system, comprising: a fluidfeed line forming a portion of said circulation system, one end of saidfluid feed line in fluid communication with said chamber; a directionalvalve disposed in said fluid feed line; a first filter element disposedin said fluid feed line for filtering fluids flowing therethrough, saidfirst filter element located upstream from said chamber; a second filterelement disposed in said fluid feed line for filtering fluids flowingtherethrough, said second filter element located between said firstfilter element and said chamber; a water line connectable to a source ofpressurized water, said water line connected to said fluid feed line ata location between said directional valve and said first filter element;and a bypass line connected to said fluid feed line to define a fluidpath that bypasses said first and second filter elements, said bypassline connected at one end to said fluid feed line upstream of saiddirectional valve and connected at another end to said fluid feed linebetween said second filter element and said chamber.
 25. A reprocessoras defined in claim 24, further comprising valve means operable toisolate said first and second filter elements from said circulationsystem and from each other.
 26. A reprocessor as defined in claim 24,further comprising means for determining the integrity of said first andsecond filter elements.
 27. A reprocessor as defined in claim 26,wherein said means for determining the integrity of said first andsecond filter elements includes a first differential pressure sensingdevice operable to sense a pressure differential across said firstfilter element, and a second differential pressure sensing deviceoperable to sense a pressure differential across said second filterelement.
 28. A reprocessor as defined in claim 27, wherein said meansfor determining the integrity of said first and second filter elementsincludes: means for isolating each filter element from said filtrationsystem, means for pressurizing the upstream side of each of saidisolated filter elements, and means for determining the integrity ofeach filter element based upon the rate of the pressure drop throughsaid isolated filter element over time.
 29. A reprocessor as defined inclaim 24, wherein said first and second filter elements are disposedwithin a single filter housing.
 30. A reprocessor as defined in claim24, wherein said first and second filter elements are disposed withinseparate filter housings and said second filter housing is downstreamfrom said first filter housing.
 31. A reprocessor as defined in claim24, wherein said second filter element is capable of filtering smallerparticles than said first filter element.
 32. A reprocessor as definedin claim 24, wherein all water entering said reprocessor from said waterline first passes through said filter elements, and a portion of allfluid circulated through said circulation system passes through saidfluid feed line and said filter elements.
 33. A method of operating asterilizer having a chamber for receiving items to be sterilized, afluid circulation system for circulating fluids through said chamber,means for generating a liquid sterilant from dry chemical reagents bymixing water therewith, and a water filtration system for filteringwater entering said sterilizer, said filtration system including: afluid feed line that is attached to said chamber, a directional valvedisposed in said fluid feed line, a first filter element disposed insaid fluid feed line for filtering fluids therethrough, said firstfilter element located between said directional valve and said chamberand downstream of said directional valve, a second filter elementdisposed in said fluid feed line for filtering fluids flowingtherethrough, said second filter element located between said firstfilter element and said chamber, a water line connected to said fluidfeed line at an intersection located between said directional valve andsaid first filter element, and a bypass line connected to said fluidfeed line to define a fluid path that bypasses said directional valveand said first and second filter elements, said method of operatingcomprising the steps of: filling said sterilizer with water from a watersource, by passing said water through said first and second filterelements; generating a liquid sterilant by mixing water filtered by saidfirst and second filter elements with said dry chemical reagents; andcirculating said liquid sterilant through said fluid circulation systemand said filtration system wherein a portion of said liquid sterilant isdirected through said first and second filter elements, and a portion isdirected through said bypass conduit.
 34. A method of operating asterilizer as defined in claim 33, further comprising the step ofexposing said water to UV radiation before said water passes throughsaid first and second filter elements.
 35. A method of operating asterilizer as defined in claim 33, wherein a step of testing theintegrity of said filter elements follows the circulating step.
 36. Amethod of operating a sterilizer as defined in claim 33, wherein saidsecond filter element is capable of filtering smaller particles thansaid first filter element.
 37. In a reprocessor having a chamber forreceiving items to be microbially deactivated or sterilized, a fluidcirculation system for circulating fluids through said chamber, meansfor generating a microbial deactivation fluid from dry chemical reagentsby mixing water therewith, and a water filtration system for filteringwater entering said reprocessor, said filtration system including: afluid feed line connectable to a source of pressurized water, a firstfilter element and a second filter element in said fluid feed line, saidsecond filter element being downstream from said first filter element, amethod of checking the integrity of at least one of said filterelements, comprising the steps of: a) establishing a first knownpressure on the upstream side of said filter element; b) allowingpressure on said upstream side of said filter element to dissipatethrough said filter element and through a leak orifice of knowndimensions; c) monitoring over time the change in pressure on theupstream side of said filter; d) establishing a second known pressure onthe upstream side of said filter element; e) allowing pressure on saidupstream side of said filter element to dissipate through said filterelement; f) monitoring over time the change in pressure on the upstreamside of said filter; and g) determining a flow rate through said filterbased on the changes in pressure determined in steps c) and f).
 38. Amethod as defined in claim 37, further comprising the step of conductinga pressurized leak test prior to step a).
 39. A method as defined inclaim 37, further comprising the step of conducting a test on said leakorifice prior to step a).
 40. A method as defined in claim 37, whereinthe change in pressure on the upstream side of said first and secondfilter elements is accomplished by using a first and second differentialpressure sensing device, said first differential pressure sensing devicemeasuring the difference in the pressure between the upstream side ofsaid first element and the pressure in a control pressure zone, saidsecond differential pressure sensing device measuring the difference inthe pressure on the upstream side of said second element to the pressurein said control pressure zone.
 41. A method as defined in claim 37,wherein said second filter element is capable of filtering smallerparticles than said first filter element.